Data conversion is the conversion of computer data from one format to another. Throughout a computer environment, data is encoded in a variety of ways. Each computer program handles data in a different manner. Data must be converted in some way whenever any one of these variable has changed before it can be used by a different computer, operating system or program. Different versions of these elements usually involve different data structures. Furthermore, data conversions may as simple as the conversion of a text file from one character encoding system to another.

There are many ways in which data is converted within the computer environment. This may be seamless, as in the case of upgrading to a newer version of a computer program. Alternatively, the conversion may require processing by the use of a special conversion program, or it may involve a complex process of going through intermediary stages, or involving complex "exporting" and "importing" procedures. In some cases, a program may recognise several data file formats at the data input stage and then is also capable of storing the output data in a number of different formats.